The N.Y.U. Head Injury Clinical Center will continue to be concernd with detailed characterization of the manner in which cerebral blood flow (CBF) and cerebral oxidative metabolism (CMRO2) and pulmonary function fail after severe human head injury, a major cause in the United States of significant neurological morbidity and mortality. Mass spectrometric studies of CBF and CMRO in acute human head injury will be continued: to determine the extent to which concurrent brain stem injury and altered intracranial perfusion pressure together and separately contribute to sharply diminished CMRO2: to evaluate the use of the CMRO2 value as a measure of prognosis, and to determine effects of steroids, antioxidant, and decompressive surgical treatment on CBF and CMRO2. Concurrent studies in animals with experimental head injury will seek to define the effects of isolated brain stem lesions; local freeze, impact, distortion and stab wound hemispheric lesions on regional CBF and regional cerebral energy metabolism. Changes in regional brain metabolism and blood flow in animals will be correlated with onset and progression of free radical pathological mechanisms in cellular membranes associated with areas of brain injury which appear to extend and magnify associated cerebral edema.